Because sometimes you need to mark a pin in between of a series of pins. Each pin shape acts like a symbol.

It is because that a square, octagonal or oblong pad has more copper area than a round hole of the same width. A larger copper area is better able to resist the track from being torn off the board, and the increased amount of solder on the larger pad also makes the joint stronger.

I am happy that you shared this helpful information with us.Please keep us up to date like this.